[vtk-developers] proposed vtkTextActor patch for cut-off text.

[Kathleen S. Biagas]

On Fri, 2013-03-22 at 09:56 -0400, David Lonie wrote:
> On Thu, Mar 21, 2013 at 1:27 PM, Kathleen S. Biagas <biagas2 at llnl.gov>
> wrote:
>         I have a change to vtkTextActor.cxx that I would like to
>         submit for
>         consideration. It corrects an issue that crops up for us on
>         some
>         systems, where a portion of text is not rendered fully (top
>         row of
>         pixels appears cut-off).  I have a small test that
>         demonstrates the
>         issue (at least on my RHEL6 system).  I didn't want to submit
>         the change
>         in gerrit without understanding the procedure for providing
>         the
>         reproducer along side. Tips on that?
> 
> 
> Try adding another text actor to these tests that shows the problem:
> 
> 
> VTK/Rendering/FreeType/Testing/Cxx/TestMathTextFreeTypeTextRenderer
> 
> VTK/Rendering/FreeType/Testing/Cxx/TestMathTextFreeTypeTextRendererNoMath
> 
> 
> 
> and the push the test to gerrit (along with the fix).
> 
> 
> If this is a common problem, we may want to attack the problem in the
> text rendering code (rather than the actor), but let's see what we can
> find out.
> 

Will do,

Kathleen
> 
> Thanks!
> Dave
>  
>         Thanks,
>         
>         Kathleen
>         
>         Here's the patch:
>         
>         
>         --- /VTK-462c2c1/Rendering/FreeType/vtkTextActor.cxx
>          2013-03-20
>         07:51:43.000000000
>         +++ /vtkTextActor.cxx   2013-03-18 09:41:01.000000000
>         @@ -635,22 +635,27 @@
>              dims[0] = ( text_bbox[1] - text_bbox[0] + 1 );
>              dims[1] = ( text_bbox[3] - text_bbox[2] + 1 );
>         
>              // compute TCoords.
>              vtkFloatArray* tc = vtkFloatArray::SafeDownCast
>                ( this->Rectangle->GetPointData()->GetTCoords() );
>         +    float tcXMax, tcYMax;
>         +    // Add a fudge factor to the texture coordinates to
>         prevent the top
>         +    // row of pixels from being truncated on some systems.
>         +    tcXMax = fminf(1.0, (dims[0] + 0.001) /
>         static_cast<float>(p2dims[0]));
>         +    tcYMax = fminf(1.0, (dims[1] + 0.001) /
>         static_cast<float>(p2dims[1]));
>              tc->InsertComponent(0, 0, 0.0);
>              tc->InsertComponent(0, 1, 0.0);
>         
>              tc->InsertComponent(1, 0, 0.0);
>         -    tc->InsertComponent(1, 1, dims[1] /
>         static_cast<float>(p2dims[1]));
>         +    tc->InsertComponent(1, 1, tcYMax);
>         
>         -    tc->InsertComponent(2, 0, dims[0] /
>         static_cast<float>(p2dims[0]));
>         -    tc->InsertComponent(2, 1, dims[1] /
>         static_cast<float>(p2dims[1]));
>         +    tc->InsertComponent(2, 0, tcXMax);
>         +    tc->InsertComponent(2, 1, tcYMax);
>         
>         -    tc->InsertComponent(3, 0, dims[0] /
>         static_cast<float>(p2dims[0]));
>         +    tc->InsertComponent(3, 0, tcXMax);
>              tc->InsertComponent(3, 1, 0.0);
>              }
>            else
>              {
>              dims[0] = dims[1] = 0;
>              }
>         
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